PURPOSE: The aim of this study was to assess serum vitamin D levels and related factors in children with cerebral palsy (CP). METHODS: One hundred and nineteen children with CP between the ages of 1 year to 10 years 9 months who were admitted to the children's inpatient rehabilitation unit of a tertiary rehabilitation hospital between January 1, 2017, and December 31, 2018, were included in this study. Demographic and clinical characteristics were obtained from the patient files. CP types and serum 25 hydroxyvitamin D (25OHD) levels were recorded. Gross Motor Function Classification System (GMFCS) was used to assess the functional level. RESULTS: Mean age was 5.1±2.9 years. Forty-two (35.3%) were girls, 105 (88.3%) were spastic, and 14 (11.7%) were ataxic and mixed type CP. Mean GMFCS level was 4 (IQR:2). Thirty-one (26.1%) were getting extra liquid feed while the rest were eating a normal diet. Mean serum 25OHD level was 27.4±15.7 (3-79) ng/mL. Vitamin D levels were normal in 68 children (57.1%), whereas 36 (30.3%) had vitamin D insufficiency and 15 (12.6%) showed vitamin D deficiency. Those whose serum vitamin D levels were within a normal range had a median age of 3.8 (IQR:4.2) years. On the other hand, mean age was 6.4 (4.3) years for those with low vitamin D level (p < 0.0001). Vitamin D level was 19.8 (21.4) ng/mL in those (n = 88) who had regular diets, whereas it was 31.0  ng/mL in those (n = 31) who were getting extra liquid feed (p = 0.015). There was no statistically significant correlation between vitamin D level and gender, GMFCS, CP type, season or antiepileptic drug treatment. A binary logistic regression model showed that older age and having only regular meals were significant risk factors for low vitamin D. CONCLUSION: In this study, 42.9% of the children with CP had low vitamin D. Older children with CP or those who had regular diets were higher risk groups in terms of low vitamin D.